The invention is directed to a process for expelling uranium hexafluoride having a high U-235 content from transportation containers, e.g., cylinders, and a container in which a uranium hexafluoride transportation flask containing highly enriched grades of U-235 can be heated whereby even in the case of disturbance no critical accident occurs.
Enriched uranium with high contents of U-235 are conveyed in corresponding transportation cylinders. In order to be changed into other uranium compounds the uranium hexafluoride must be driven out of this transportation cylinder and caught in a receiver. This expelling of the uranium hexafluoride takes place in so-called heatable containers in which the transportation cylinder is heated so that the uranium hexafluoride can escape in gaseous form.
For small degrees of enrichment of uranium 235 as it is used for power reactors there are known such heatable containers. With the slightly enriched degrees (&lt;4% U-235) this can be accomplished by heating the uranium hexafluoride cylinder with saturated steam at 100.degree. C. if the maximum amount of water in the heatable container is limited. At enrichment degrees of &lt;90% U-235 this is no longer possible because the UF.sub.6 indeed has safe geometry but the heatable container must be larger and therewith a safe geometry can no longer be guaranteed, particularly the water acts as moderator. Besides the critical uranium amount is reached in these containers already at about 810 grams while the normal cylinder, however, contains 16 kg of uranium. The driving out of the uranium hexafluoride from the transportation cylinders with high U-235 contents therefore is not possible.
It is furthermore known to provide such heatable container with an electroheater whereby the steam acting as moderator as heating agent is eliminated. However, these apparatuses have the disadvantage that the heating temperature cannot be limited and in case of disturbance the temperature may increase to such an extent that the transportation cylinder bursts.
Therefore it was the task of the present invention to find a process and apparatus with which uranium hexafluoride having a high U-235 content can be driven out of transportation containers, e.g., cylinders, without danger that a cylinder bursts or a critical accident can arise by the moderator action of the heating medium.